You’d expect to be able to trust any health claims made on the pack but sadly it is not always so simple.

A recent Which? investigation revealed there are numerous supplements still boasting health claims that have been analysed and rejected by the European Food Safety Authority (EFSA).

A common example is that glucosamine can improve the health of your joints – there is no decent evidence.

Bizarrely, the manufacturers will only have to remove such claims when the European Commission has taken the authority’s findings to EU member states for a vote.

Then a list of accepted and rejected claims will be published but because there are so many, this won’t happen until the end of 2011.

It’s bad enough that people are being misled into parting with their cash but more worrying is the fact that many supplements fail to carry warnings that high doses can harm you. A third of the 1,200 people who were quizzed by Which? were not aware of this. I was first alerted to this problem years ago when vitamin B6 became popular for PMS.

Women thought that the more they took, the more good it would do. But very high doses can lead to nerve damage. In fact, many vitamins are potentially toxic if they build up too much in the body.Antioxidants are thought to reduce the risk of some serious illnesses.

But most evidence is based on fruit and veg rather than supplements.

Ironically betacarotene, a nutrient the body turns into antioxidant vitamin A, can actually increase risk of lung cancer in smokers. Taking individual vitamins or minerals is a bad idea as nutrients work in combination.

For instance, there’s no point in just taking calcium for bones as you need adequate levels of vitamin D for it to be absorbed.

And too much zinc could interfere with the absorption of copper.

I’m dubious about the benefits of multi-vitamins too. My worry is that they may lull some people into a false sense of security so they believe it’s OK to eat poorly.

Also, our bodies are designed to get vitamins and minerals from food, where they are surrounded by hundreds of micro-nutrients that help us utilise them more effectively. Sometimes supplements are necessary – folic acid and vitamin D in pregnancy, for instance. Certain supplements are also recommended to help a form of age-related blindness.

But some can also clash with medication and even make some conditions worse. Labelling needs to be much clearer.